DOPTPRM, OPTMETH

Bulk Data Entry Options to choose the optimization algorithm.

Definitions

Parameter Values Description
OPTMETH <MFD, SQP, DUAL, DUAL2, MMA, BIGOPT>

Default = See description and Comments
MFD
Method of feasible directions.
MFD is the default optimizer for problems with a large number of constraints (but smaller number of design variables) such as size/gauge and shape.
SQP
Sequential Quadratic Programming
DUAL
Dual Optimizer based on separable convex approximation.
DUAL2
Enhanced Dual Optimizer based on separable convex approximation. 2 3
DUAL2 is the default optimizer for problems with a large number of design variables such as topology, free-size and topography.
MMA
Method of Moving Asymptotes. 3
BIGOPT
Large scale optimization algorithm.

MFD, SQP (primal methods) and BIGOPT are more suitable for size/gauge and shape, since the approximate problem typically involves coupled terms, due to the advanced approximation formulation utilizing intermediate variables and responses.

If Equality Constraints are activated in size and shape optimization, then SQP is the default optimizer.

Comments

  1. During a run, the corresponding optimization algorithms are automatically selected by OptiStruct based on the optimization type. The use of this parameter will override the defaults.
  2. DUAL2 is an enhanced version of the proprietary CONLIN dual optimizer. Solution stability has been improved, reducing probability of failure in converging to a solution. The default optimizer for problems with a large number of design variables such as topology, free-size and topography is DUAL2. You can switch to DUAL in case you run into issues with the default DUAL2 for Topology, Free-Size, or Topography optimization.
  3. You can switch to DUAL or MMA, in case you run into convergence issues with the default DUAL2 for Topology, Free-Size, or Topography optimization.